Rotating Microdisk Voltammetry in Low Ionic Strength Solutions.
Abstract
The influence of the supporting electrolyte concentration on the steady-state voltamnetric behavior of a 12.5 micrometers-radius rotating Pt disk electrode (angular velocity, (omega=0 to 378 radian/s) has been investigated for several electrochemical reactions in acetonitrile solutions. The results demonstrate that the voltammetric response is a strong function of the ratio of the supporting electrolyte and redox concentrations (C(sub elec)/C(sub redox)) as well as the charge of the reactant, (z). For the oxidation or reduction of monovalent and divalent species (e.g., (TRIMETHYLAMMONIO)METHYLferrocene (z = +1) and methylviologen (z = +2)), the observed voltammetric limiting currents are found to increase linearly with (0112,independent of C(sub elec)/C(sub redox). Voltammetric currents corresponding to the oxidation or reduction of neutral reactants (e.g., ferrocene and nitrobenzene (z = 0)) show a more complex dependence on C(sub elec)/C(sub redox). In solutions containing an appreciable quantity of supporting electrolyte, C(sub elec)/C(sub redux) > 0.1, mass-transport limited currents are found to increase linearly with omega (1/2). However, for C(sub elec)/C(sub redox) <0.1, the voltammetric currents decrease with increasing omega. The unusual behavior observed for neutral species in low ionic strength solution is interpreted in terms of the rate of migration of charge-balancing electrolyte ions to the electrode surface, relative to the rate of removal of the same ions by forced convection. jg
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 1995
- Accession Number
- ADA294323
Entities
People
- Henry S. White
- Xiaoping Gao
Organizations
- University of Utah